PINUS 181 



(i) Make a drawing (X 10) of the longitudinal view. 

 (k) Into what will the bud develop? What will 



become of each of its parts? 

 (/) How much of your specimen represents last 



year's terminal bud? The bud of year before 



last? 

 (m) When the annual growth of a branch ends with 



the formation of a bud the growth is called 



determinate. Is the growth of the dwarf 



branches determinate or indeterminate? Of 



the long branches? 

 E. Homologies: 



1 . Organs which perform like functions are analogous 

 to each other. Organs which correspond to each 

 other structurally i.e., which have the same mor- 

 phological value, are homologous. For example, 

 the flat, chlorophyllous stems of cacti and the foliage 

 leaves of the maple tree are analogous, for they both 

 function as organs of photosynthesis; but they are 

 not homologous, for one is a stem, the other a leaf. 

 The bud-scales of Pinus and the pine " needles" 

 are homologous, i.e., from the standpoint of struc- 

 tural value (morphological standpoint) they are 

 both leaves. But they are not analogous, for, 

 whereas the "needles" act as organs of photo- 

 synthesis, the bud-scales do not, as they have no 

 chlorophyll. 



2. One of the most important, and often most difficult, 

 problems of morphology is correctly to interpret 

 the structural value of an organ; in other words to 

 recognize homologies; for any organ may be pro- 

 foundly modified, and appear so disguised as to 

 make it extremely difficult to recognize its morpho- 

 logical significance. Pinus furnishes an excellent 



